Automatic panel circuit for air reheat control



Oct. 19, 1948. T. J. I EHANE ETAL 2,451,566

AUTOMATIC PANEL CIRCUIT FOR AIR REHEAT CONTROL med April 16, 1945 2 sheets-shea 1 Oct. 19, 1948.

Filed April 16. 1945 T. J. LEHANE ETAI. 2,451,566

AUTOMATIC PANEL CIRCUIT FOR AIR REHEAT CONTROL 2 Sheets-Sheet 2 Maw/My Patented Oct'. C19-,Iv A1948 UNITED lsizrrla.

s PATENT oFFicE AUTOMATIC PANEL CIRCUIT FCB AIR REHEAT CONTROL Timothy J. Lehane and Everett H. Burgess, Chi

by mesne assignments, to

cago, Ill., assignors,

l Vapor Heating Corporation,

'Delaware a corporation of Application Aprilia, 19.45, serial No. 53am This invention relates to improvements in apparatus for controlling the operation of means for heating varid/or cooling. an enclosed space to maintain a desired temperature therein.

The improvements herein'shown and described are directed speccally to apparatus suitable for controlling the temperature of a railway passenger coach, but it willl be'obvious to persons familiar with the art that the said improvements may be advantageously used in many other situations.

A principal object of the inventionis to provide a control apparatus which willfunction in an improved manner to control the operation of a heating element and a. cooling element, whereby either may be made ineiective during the operation ofthe other and whereby, .under certain conditions, both heating and cooling Aelementsfunction at predetermined temperatures to control the operations of elements for heating and coolingv air circulated through the space and to provide means associated with said thermostats and adapted, upon the functioning of the cooling element thermostat, to adjust the heating element thermostat to raise its functioning temperature, whereby the air cooled by said cooling element will be reheated by said heating element.

.Another object is to provide, in combination with heating and cooling elements and means for forcing air through said elements, means operative in harmony with the heating and cooling demands of the temperature controlled space to bypass a portion of the air around one of said elements and thereby vary the effectiveness of said element.

According to the present invention, primary and secondary means are employed to heat .air circulated through an enclosed space. The operation of the heating and cooling elements are controlled by means responsive to temperature changes Under certain conditions the heating and the cooling elements may be operated conjointly to cool and thereafter heat the air, or they may be within the space being controlled.v

n calms. (on. a-ei made separately ineffective, depending upon the temperature requirements of the space whose temperature is being controlled. If also desirable to control the temperature of the space in relation to a desiredy relative humidity and temperature, combinedwet-dry thermostats may be substituted for one or more ofthe dry bulb thermostats herein shown.

The invention will be better understood by considering the -following disclosure in connection with the accompanying drawings and its scope will be pointed out in the appended claims.-

other to maintain the desired tem- In the drawings: Fig. 1 is a fragmentary sectional view of a railway coach showing one preferred arrangement of the heating and cooling elements together with the control thermostats and other related devices.

y Fig. 2 is a cross-sectional a smaller scale; and

Fig. 3 is a wiring' diagram illustrating the variview of the coach on vous circuits and electrically actuated devices for controlling the operations of the heating and cooling elements.

The invention may be described briey as inn 'cludin'g a primary heating element A, a secondaryl heating element B, an air cooling element' C, a blower D for forcing air through elements B and C and an electric control apparatus E.

The primary heating element, or elements as the case may be, are Vin the form of radiators located neax the floor of the enclosed space and function to add heat directly to the atmosphere within the space. The secondary heater is preferably arranged overhead and delivers preheated lair into the said space from a duct. The air cooler is arranged so that, during the cooling function of the system the air is forced by a blower through the cooling apparatus C. If the weather is mild so that it is desired to reheat the air, all or part of the air may be directed through the cooler C and thereafter through secondary heater B, so as to reheat the air to the desired temperature before it is delivered into the en-l closed space.

The electric control apparatus includes a primary heater thermostat F responsive to temperature changes in the room and its cooperating relay G for controlling the supply of heating medium, for example steam, to the iioor radiator; 'a similar thermostat H, responsive to temperature changes in the car, and its associated relay I for controlling the supply of heating medium to the secondary radiator, and a thermostat J and cooperating relay K for controlling the operation oi the air cooling apparatus C, which apparatus is shown diagrammatically in Fig. 1 of the drawings. ciated relay M are connected in the electric circuits and serve to make the primary heaters and` the controls therefor ineective when the outside tempe'rature rises to a predetermined minimum, for example40 F. In addition to the above elements the invention includes various resistors and auxiliary electric heaters for adjusting the functional settings of the thermostats-to accel- An outside thermostat L and its assoerate or retard theoperations oi' the thermostats motor R controlled by the temperature of the space for varying the position of the valve.

` Referring now to the control circuits shown in Fig. 3: All operating parts of the wiring diagram are shown in the positions which they assume when the passenger coach is out of service. W|hen the coach is put intoservice a manually operated switch I5 is closed. The closing of this switch establishes an electric circuit leading from the positive line I6 through the switch arm I5, wire I1, the blower operating motor D, and thence to the negative line I8. This circuit energizes the blower motor so that the blower will force air through the cooling element C and the heating element B. Simultaneously with the closing of the energizing circuit ior the blower motor a second circuit is established leading from the posi.

tive wire I1 through wire I9, resistor .26, solenoid 2| of relay M, thence through wire 22, resistor 23 and rwire 24 to the negative line I 8. This circuit energizes said relay M so as to close its movable contact 25 and thereby close a circuit through the actuating solenoid oi relay G. This circuit leads from positive wire I1, through. wire a 26, movable contact 25 of relay M, wires 21 and 23, through resistor 29, wire 30, solenoid coil 3| of relay G, thence through wire 32, resistor 33, and wire 34 to the negative line I8. The closing of this circuit energizes the solenoid 3| so as to open the movable contact 35 of relay G and thereby open. the energizing circuit through solenoid 36. The solenoid 36 is normally energized by a circuit consisting of wire 31 leading from the positive line I6 through the movable contact 35 of relay G, wire 38, solenoid coil 36, thence through wire 39 the negative line I8. When this circuit is effective the valve 40 is closed, but when the circuit is broken,'the valve 40 isv held open Aby a spring 4I. Consequently, when the solenoid 3l of relay G is energized to move the contact 35 to its open position, the valve actuating solenoid 36 is deenergized and permits the valve to open to supply steam to the primary radiators A. This operation will continue until the mercury column of thermostat F engages the outer contact 42 thereof. 'I'he closing of the thermostat at the said contact by-passes the electric current around the solenoid 3I through wire 43, mercury column of thermostat F and wire 44 so as todeenergize the said solenoid 3|. This condition permits the I contac't 35 to close the energizing circuit through valve solenoid 36 and thereb, Ishuts off the supply of steam to the 'primary radi, tors A. Each time that the mercury column of said thermostat F drops below the outer contact 42, the relay G is actuated to deenergize the solenoid 36 and permits spring 4I to open the radiator valve 40. -The said valve 40 may remain open for a substantial period or for only a brief period depending upon the cooperative functioning of the thermostat H and relay I to supply electric current to an auxiliary heater 45 in theI manner hereinafter described. A

It it should be desirable to open the supply valve 46 to deliver steam to the primary radiators when either the switch I5 or the contact 25 of relay M are open, the relay G can be energized to break the circuit through the valve solenoid 36 .by closing a manually operated switch 46 sc as to direct current from the positive line I6 `to the solenoid of relay G.

Simultaneously with the opening of the valve 46 to supplyl steam to the primary radiators, a valve 51 is opened to supply steam to the secondary radiator B. This is accomplished by means of a circut leading from the positive wire I1 through wire 41, resistor 48, wire 49, solenoid 50, wire 5I, resistor 52,'and thence through wire 53to the negative line I8. The energization of solenoid 50 operates relay I to open its contact 54 and close its contact 55. The latter of which establishes an energizing circuit through solenoid 56 for opening said steam supply valve 51 for the secondary radiator B. This energizing circuit leads from posi-l tive wire I1 through Wire 58, closed movable contact 55 of relay I, wires 59 and 60, through sole` noid 56, and thence through wire 6I to the negative line I8. The supply valve 51 for the radiator B will be held open against ther compression of spring 62 until the me'rcury column of thermostat H engages the outer contact 63 thereof. When this occurs the current is by-passed around the relay solenoid through wire 64, mercury column of thermostat H and wire 65 to the negative side ofthe said solenoid 50. This releases the relay contact to open the energizing circuit througlh the valve solenoid 56 and thereby permits the supply valve 51 to close and also releases relay contact 54 so that it moves into a position to close the enclosed space. For example, when the temperature of the enclosed space is such as to require full capacity oi the cooling element, the heat motor R. will operate to move valve Q to close the by-pass P and thereby direct all of the air through the cooling element. The energizing circuit through the said auxiliary heater 45 leads from the positive line I6 through wire 61, movable contact 54 of relay I, 'Wire 69, resistor 69, and wire 19 to the said auxiliary heater 45 and thence through wire 1I to the negative line I8. A portion of the electric current is directed throughthe heating coil 66 of said heat motor R. This branch of the circuit leads from wire 68 through wire 12, heat motor coil 66 and then-ce through wire 13 to the negative line I8. It will be noted here that the auxiliary heater 45 for the thermostat F and the heating coil 66 of the lheat motor are effective only when the secondary radiator thermostat H is satisfied and the steamsupply is shut off from the secondary radiator B. Consequently, when the secondary radiator thermostat l H'is'satisned and the relay is moved by spring 82 tothe position indicated in full lines in Fig. 3,

the auxiliary heater 45 is energized to supply. added heat to the primary heater thermostat F and thereby cause its mercury column to engage its outer contact l2 and thereby actuate relay G 'to energize valve solenoid 30 so. as to ,close the supply valve 40. This cycling .action or the primary radiator thermostat takes place each time that the supply valve 51 for the secondary radi- 'ator is opened and closed.

The thermostat H for controlling the secondary radiator is positioned at a suitable location in the car to respond to the temperature changes therein. It is constructed to normally function at a predetermined temperature, for example '78 F.,

but this original setting is preferably adjusted by the application of auxiliary heat to the thermoperature of the enclosed space is suiilcient to maintain the mercury column of thermostat H in engagement with its outer contact63. When the cooling apparatus is not' functioning, an additional heating circuit of 3 F. is supplied through wire |01, contact |08 of relay K, wire |09, resistor' 0, and wire 18 to heater 19, thence through wire 80 to negative line I8. It will be seen, therefore,

that when the cooling apparatus is not functioning, the auxiliary heating current supplied through 4resistors 82 and H0 will adjust the stat so that it will function at a lower room temperature. Preferably the amount of auxiliary heat is varied so that thethermo'stat will function' at a. day room temperature of '72 F. and at a night room temperature of '74 F. when the cool- 'ing apparatus is n-ot operating. However, when .the cooling apparatus is operating, the functional setting of said thermostat H is automaticallyv raised to '75 F. and '77 F., respectively, so that the heating thermostat H will have a room temperature setting 2 F. higher than the room ternperature settingof the cooling control thermostat .The auxiliary heat 'is applied to thermostat H by means of an electric circuit leading through positive wire |1, through wire 18 to a manually operated two-position switch 1'5'when the switch is in the position illustrated in full lines in Fig. 3, electric current passed from the switch through wire 16 and resistor 11 to wire 18, auxiliary heater 19, thence through wire 80 to the negative line I8. The resistor 11 is so proportioned vas to supply suillcient current to the auxiliary heater 19 to 'add 3 F. to the thermostat H, and consequently, in

vthe absence of other auxiliary heating current,

the thermostat H willl function when the temperature of the space reaches '75 F. When the switch l 151s moved to its other` position, the current is circuit adds only thermostat to a room temperature setting of 72. It will be observed also 'that the night setting will be 74, since theresistor 11 in the night lheater 1 of heat to the thermostat.

Cooling control The operations of the cooling element are controlled `by arelay K whose operations are-controlled by the thermostat J. This thermostat is preferably arranged wit-hin the enclosed space Whose temperature is being controlled' so as to respond to. changes in the temperature. It is also connected through the relay M so that it will not oe effective until the outside temperature rises above 40 F. The thermostat is manufactured to function at a temperature of '76 F., but this lis adjusted to a lower room temperature by auxiliary heating circuits whereby the functioning temperature of the thermostat may be raised or lowered t-o suit day or night occupancy. One of.

these circuits includes wire 85 and switch 86, wire 81, resistor 88, Wire 89 through the auxiliary heater 84a and thence through wire 90 to the nega.-

tive line i8. The resistor 88 preferably supplies v 3 of auxiliary heat to the thermostat'J so that it directed from the switch 15 through wire 8| and resistor 82 to said wire 18, and thence through the auxiliary heater 19 of thermostat H and wire 80 to the negative line |8. The said resistor 82 preferably permits a smaller amount of current to pass to the auxiliary heater 19, for example 1. so that the thermostat H, when set for night control and in the absence of other auxiliary heating current, will function at a, higher room temperature; for example 17 F.

When the solenoid of the relay I is energized to close the movable contact and thereby establish an energizing circuit through solenoid 56 to open the steam supply valve to the secondary radiator, the closing of said relay contact 55 A establishes a. circuit for adding additional heat to the auxiliary heater 19 of the thermostat H. 'I'his heating circuit is intended merely to accelerate the functioning of thermostat H and leads from positive line i1, through wire 58, movable contact 55 of relay-A I, Wire 83, cycle resistor. to

will function at a room temperature of 73. When the said switch 86 is in the position shown in Fig. 3, a resistor 92 controls the amount of electric current supplied to the auxiliary heater 84-, Inasmuch as the resistor 92 adds only 1 of auxiliary heat, the thermostat J will function at a night room temperature of 75. When the temperature at the thermostat J is such as to cause its mercury column to engage its outer contact 93, the solenoid 94 of relay K is energized to actu- 4ate the relay K. This energizing circuit leads from`positive' line |1 through wire 95, relay M. wire 95, mercury column. of thermostat J, outer contact 93 of said thermostat, thence through wire 96,` solenoid 94 and wire 91 to the negative line 'I8. Y The energization 4of solenoid 94 moves l ,contact 98 of relay K, wire |00 through a conwire 18 and thence through the auxiliary heater u 19 and wire 80 to the negative line I8. 'This additional heat supplied to the thermostat H is removed as soon as the mercury column of the thermostat engages the outer contact 63 whereupon the mercury column immediately recedes from said contact 63 and thereby brings about ,a cycling actionwhich opens and closes the steam denser fan |0|, a compressor |02, thence through wire |03 to the negative line |8. Simultaneously with the energization of the cooler mechanism,

a circuit is established to open valve |04 in the coolant circulating system associated with the cooler C. This valve opening circuit leads from positive wire |00 through wire |05, valve |04, andA wire |06 back to the negative Wire |03. It'will be- `here observed, as previously described, that the relay K, when enerized to start operation -of the cooling apparatus, opens the circuit through resistor H0 and thereby removes 3 of auxiliary ,heat from thermostat H. This automatically -raises vthe functional setting of thermostat H so as to induce operation of the secondary heaters during the cooling operation until the .temperature of the enclosed space has changed sufiiciently 7 to make it undesirable to add heat to the cooled air introduced into the space.

Summary of operation By inspection of Fig. 3 of the drawings 'it will be apparent that the closing of switch I5 will energize the blower fan D so that this element valve 40 to open and thereby supply steam to the primary radiators A. The opening and closing of the valve 40 is under the control of thermostat F and said relay G until -the outside temperature rises above 40 F. When this occurs, the thermostat L closes a circuit which deenergizes relay M and thereby opens the circuit through solenoid 3i of relay G, bringing about -the closing of steam supply valve I0. Simultaneously with the supply of steam to the primary radiators A, the relay I is actuated to close an energizing circuit through valve solenoid 56 to open the valve 51 and thereby supply steam to the secondary radiator B. The said valve' 51 is under the control of thermostat H. The-functional setting of the thermostat H is in part controlled by electric -heating circuit closed through relay K. Consequently, when the cooling element C is not operating and the relay K is -in the position indicated in Fig. 3.L th'e auxiliary heater 19 of thermostat H is supplied with additional current through a circuit leading from positive line I6 through wire |01, movable contact |08 of relay K, wire |09 and resistor H0 to wire 18, and thence through the auxiliaryheater 19 and wire 80 to the negative line i8. It will be seen, therefore, that when the outside temperature is such that the relay M makes thermostat J eiective and when the functioning of thermostat J actuates the relay K to close a circuit through the operating mechanism of the cooling element C, the resistor circuit Il ll is removed from th'e f heating circuit of auxiliary heater 19 and thereby raises the functional setting of secondary heater l thermostat H so that the secondary heater will not function to add heat to the cooled air until the temperature of the enclosed space is heated sufficiently to close the circuit through thermostat H.

We claim:

1. `In combination with heating means for directly adding heat to the air within an enclosed space, means for circulating air through the space and heating means for heating the circulated air; a thermostat responsive to temperature changes within the space for controlling the first mentioned heating means, an auxiliary electric heater for said thermostat, a second thermostat responsive to temperature changes within the space for controlling means for heating the circulated air, means effective upon the functioning of the last mentioned thermostat for closing.. an energizing circuit through said auxiliary heater, and an auxiliary heater for the second thermoy stat, and means including a third thermostat responsive to a predetermined space temperature for opening a circuit through the second mentioned auxiliary heater and thereby adjust the second mentioned thermostat to a higher functional setting.

2. In combination with heating means for directly adding heat to the air within an enclosed space, means for circulatingair through the space and heating means for heating the circulated air': a thermostat responsiveto temperature changes within the space for controlling the first mentioned heating means, an auxiliary electric heater for said thermostat, a second thermostat responsive to temperature changes within the space for controlling means for heating the circulated air, an auxiliary electric heater for the second thermostat, a relay controlled by the second thermostat adapted in one position to close an' energizing circuit through the auxiliary heater of the ilrst mentioned thermostat and in another position to close an energizing circuit through the auxiliary heater of the second thermostat, and means including a third thermostat responsive to the temperature of the enclosed space for opening a circuit through the auxiliary heater for the second thermostat and thereby adjust the secondA thermostat to a higher functional setting.

y3. In combination with heating means for directly adding heat tothe air Within an enclosed space, means for circulating air through the space and heating means for heating the circulated air; a' thermostatresponsive to temperature changes within the space for controlling the rst mentioned heating means, an auxiliary electric heater for said thermostat, a second thermostat responsive to temperature changes within said space, an

auxiliary electric `heater for the second thermostat, a relay controlled by the second thermostat adapted to close an energizing circuit through the auxiliary heater of the first mentioned thermostat when the second thermostat is satised and is effective to close an energizing circuit through the auxiliary heater of the second thermostat when the second thermostat calls for heat, and means including a. third thermostat responsive tothe `temperature of the enclosedspace for opening a circuit through the auxiliary heater for the second thermostat and thereby adjust the second thermostat to a higher functional setting.

4. In combination with a primary heater for directly adding heat to an enclosed space, means for circulating air through the space, and a secondary heater for adding heat to the circulated air; means for controlling the operation of the primary heater including a normally open valve for supplying heating medium thereto, an electrically energized device for closing said valve, a relay for closing a circuit through said device; and a thermostat responsive to temperature changes in the space for controlling the operation of said relay; means for. controlling the operation of the secondary heater including a normally closed valve for supplying heating medium thereto, a solenoid for opening the said normally closed valve, a relay for closing a circuit through the solenoid and a thermostat responsive to temperature changes for controlling the operation of this relay; separate auxiliary electric heaters for said thermostats and energizing circuits therefor connected through the last mentioned relay, whereby auxiliary heat is added to the rst mentioned thermostat when the supply valve for the secondary heater is closed and auxiliary heat is added to the last mentioned thermostat when the said supply valve for the secondary heater is open; and means including a third thermostat responsive toa predetermined temperature of the en closed space for opening a circuit through the closed valve for supplying air;

ondary heater for adding heat to the circulated air; means for controlling the operation of the primary heater including a normally open valve for supplying heating medium thereto, an electrically energized device for closing said valve, a

relay for closing a circuit through said device,

and a thermostat responsive to temperature changes in the space for controlling the operation of said relay; means for controlling the operation of the secondary heater including a normally heating medium thereto, a solenoid for opening the said normally closed valve, a relay for closing a circuit "through the solenoid and a thermostat responsive to temperature changes for controlling the operation of this relay; separate auxiliary heaters for said thermostats, means for supplying a predetermined constant energy to the auxiliary heater of the last mentioned thermostat, means for adding temporary energy to each of the said auxiliary heaters alternatively, and means including a third therl mostat responsive to a predetermined temperature for adjusting the functional setting of the second thermostat.

6. In combination with a primary heater for directly adding heat to an enclosed space, means for circulating air through the space, and a secondary heater for adding heat to the circulated means for controlling the operation of the primary heater including a normally open valve for supplying heating medium thereto, an electrically energized device for closing said valve, a relay for closing a circuit through said device, and a thermostat responsive to temperature changes in the space for controlling the operation of said relay; means for controlling the operation of the secondary heater including a normally closed` valve for supplying heating mediumqthereto, a solenoid for openingthe said normally closed valve, a relay for, closing a circuit through the solenoid and a thermostat responsive to temperature changes within the space for controlling the operation of this relay; separate auxiliary heaters for said thermostats, means for supplying a predetermined constant energy to the auxiliary heater of the last mentioned thermostat, and means for adding temporary energy to each of the said auxiliary heaters alternatively, comprising energizing circuits therefor connected through A anenclosed space, means for circulating air through the space, and a sec- 10 to said auxiliary heater including a relayand a control thermostat therefor responsive to temperature changes within said space, whereby the relay is actuated Vupon the functioning oi.' the second mentioned thermostat to open a circuit through said auxiliary heater and thereby adjust the last mentioned relay, whereby auxiliary heat is added to the rst mentioned thermostat when the supply valve for the secondary heater is closed and additional auxiliary heat is supplied to the second mentioned thermostat when the supply valve for the secondary heater is open, and means including a third thermostat for opening a circuit through the auxiliary heater for the second mentioned thermostat and thereby adjust the said second thermostat to a higher' temperature setting.

7. In combination with means for circulating air through an enclosed space and means for adding heat to the circulated air including a radiator, an electrically actuated valve for supplying heating medium to said radiator, means for controlling the operation of said valve including a thermostat responsive to temperature changes within the space, an auxiliary electric heater ,for said thermostat and means for supplying energy the first mentioned thermostat to a higher functional setting.

8. In combination with means for circulatin! air through an enclosedspace, means for cooling the air, and means for adding heat to the circulated air including a radiator, an electrically actuated valve for supplying heating medium to said radiator, means for controlling the operation of said valve including a thermostat responsive to temperature changes within the space, an auxiliary electric heater for said thermostat, a relay and a control thermostat therefor responsive to temperature changes within said space for energizing said air cooling means upon the functioning of the last mentioned thermostat and for opening an energizing circuit through the said auxiliary heater whereby the first mentioned thermostat is adjusted to a higher functional setting.

9. In combination with means for circulating air through an enclosed space, means for cooling the air, and means for adding heat to the circulated air including a radiator, an electrically actuated valve for supplying heating medium to said radiator, means for controlling the operation of said valve including a thermostat responsive to temperature changes within th'e space, an auxiliary electric heater for said thermostat, a relay and a control thermostat therefor responsive to temperature changes within said space for energizing said air cooling means upon the funcmentioned thermostat and for I tioning of the last opening an energizing circuit through the said auxiliary heater whereby the first mentioned thermostat is adjusted to a higher functional setting and manually operable means for adjusting the functional setting of the last mentioned thermostat.

l0. In combination with means for circulating air through an enclosed space, means for cooling the air, and means for adding heat to the circulated air including a radiator, an electrically actuated valve for supplying heating medium to said radiator, means for controlling the operation of said valve including a thermostat responsive to vtemperature changes Within the space, an auxiliary electric heater for said thermostat, a relay and a control thermostat therefor responsive to temperature changes within said space for energizing said air cooling means upon the functioning of the last mentioned thermostat and for opening an energizing circuit through the said auxiliary heater whereby the rst mentioned thermostat is adjusted to a higher functional setting, and manually operable means for adjusting the functional setting of both thermostats.

11. In combination with means for circulating air through an enclosed space, means for cooling the air, and means for supplying heat to'maintain'the space at a desired temperature; means for controlling the operation of the heating means including an electrically actuated valve, a relay for closing a valve energizing circuit, and a ther-` mostat for controlling the operation of the relay; an auxiliary heater for said thermostat; manually operable means for adjustably varying the supply of electric current to said auxiliary heater so as to adjust the functional setting of said thermostat, and an additional circuit connected through said relay for adding additional current to said auxiliary heater when the thermostat calls for heat; a y

relay for closing a circuit for energizing said cooling means and means defining an electric circuit connected through said last mentioned relay for supplying additional heating current to said auxiliary heater and adapted to be openedwhen the cooling means is energized so as to increase the functional setting of the first mentioned thermostat.

12. In combination with means for circulating fil' air through an enclosed space, means for cooling the air, and means for supplying heat to maintain the space at a desired temperature; lmeans, for controlling the operation of the heating means including an electrically actuated valve, a relay for closing a valve energizing circuit, and a ther ilning an electric circuit connected through said lasi-l mentioned relay for supplying additional heating current to said auxiliary heater of said rst mentioned thermostat and adapted to be opened when the cooling means is energized so as to increase the functional setting of the rst mentioned thermostat.

13. In combination with a primary heater for adding heat directly to the atmosphere within an enclosed space, means including arelay and a primary control thermostat associated therewith for controlling the operation of said primary heater, an auxiliary electric heater for the primary con- -trol thermostat, means for circulating air through said space, a secondary heater for adding heat to the circulated air, means including a second relay and a secondary control thermostat associated therewith for controlling the operation of the secondary heater, an auxiliary electric heater for the secondary control thermostat, an energizing circuit for the auxiliary heater of said primary control thermostat and adapted to `be closed when the secondary control thermostat is satisiled, an energizing circuit i'or the auxiliary heater oi the secondary control thermostat connected through said second relay and adapted to be closed when the secondary control thermostat calls for heat. means for cooling the circulated air, means including a third relay and a third thermostat for controlling the operation of the cooling means, and means connected through the third relay for supplying a portion of the auxiliary heat to the secondary control thermostat and adapted to be opened to increase the functional setting of the secondary control thermostat when the cooling means is operating.

14. In combination with a Primary heater for heating an enclosed space and means for controlling the operation thereof including a thermostat responsive to temperature changes within the enclosed space and provided with an auxiliary electric heater, means including a duct for delivering air into said space, an air heating element and an air cooling element arranged in said duct so that air will pass' through one to the other, means for controlling the heating element including a thermostatically controlled relay for opening and closing an electric circuit through said auxiliary heater, and means for varying the eiectiveness of one of said elements comprising a by-pass duct for directing a portion of the air around one of said elements, a valve for opening and closing said by-pass duct, a heat motor responsive to temperature changes for adjusting the position of said valve, and an electric heating element for said motor connected through said relay to receive heat simultaneously with the said auxiliary electric heater for said thermostat. TIMOTHY J. LEHANE. EVERE'IT H. BURGESS.

REFERENCES CITED The following references are of record in the leof this patent:

UNITED STATES PATENTS Number Name. l Date 843,909 Peters et al. Feb. 12, 1907 2,181,480 Giuett et a1 Nov. 2s, 1939 n 

